Causes for a speaker to go open circuit??

Seegs

Member
Messages
10,169
I've had a Eminence Cannabis Rex in my 64 Deluxe and after changing power amp tubes yesterday I heard this wierd growling and scrathing sound and then nothing...

I checked the resistance on my speaker and it read open...I put a Weber 12150F in there...changed the speaker cable just in case and it works fine...

Could a shorted speaker cable cause the speaker to go open like that...bad output transformer or maybe just a defective speaker...??

Any ideas would be helpful!!

Chow,
Seegs
 

John Phillips

Member
Messages
13,038
Defective speaker or too much power.

That's it.

No fault on a tube amp can blow a speaker, because the speaker is isolated from the amp's circuit by the OT, and the secondary winding of the OT - the only bit that's actually connected to the speaker - is in fact a passive component.

(A solid-state amp is different, and a shorted output transistor can easily blow a speaker by connecting it directly to the DC power supply.)

A bad speaker cable can seriously damage an amp, but not a speaker.

Remember that amps peak well above their rated RMS power usually though, and some speaker makers are more conservative than others about how they rate them - Celestion's definition seems to be 'a cranked tube amp of the same power' (ie possibly as much as double the RMS power they're quoting); Eminence's seems to be less.

Even so, I don't think a 22W amp could blow a speaker rated at 50W in normal use (or even with bass through it, which reduces the effective power handling), so I'd guess you have a faulty speaker.
 

Seegs

Member
Messages
10,169
Thanks John...I was hoping it was just a freak thing...I will order another one and hope it lasts longer...I have another CR in my 30-40 watt Fargen Dual classic that gets played more often and driven way harder than the speaker in my Deluxe did and it's fine...

So maybe I was just unlucky...!!

Chow,
Seegs
 
T

Trevor Bond

Several things... Heat... marginal manufacturing... square wave slammin the cone...
 

Wakarusa

Member
Messages
1,458
Originally posted by Seegs
Thanks John...I was hoping it was just a freak thing...I will order another one and hope it lasts longer...I have another CR in my 30-40 watt Fargen Dual classic that gets played more often and driven way harder than the speaker in my Deluxe did and it's fine...

So maybe I was just unlucky...!!

Chow,
Seegs
Depending on how long you've had it, Eminence may replace it under warranty
 




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